Electron paramagnetic resonance (EPR) spectroscopy

This chapter focuses on electron paramagnetic resonance (EPR) spectroscopy, which is also known as electron spin resonance (ESR), and, more rarely, electron magnetic resonance (EMR) spectroscopy. EPR spectroscopy is a useful technique for characterizing compounds that contain unpaired electrons (paramagnetic species), such as materials containing the d- and f-block elements and main-group compounds that exist as radicals. It provides molecular structural information about the species present and can give a very detailed insight into the electronic structure. However, the key limitation of EPR spectroscopy is that the species under investigation must contain at least one unpaired electron. While there are numerous stable transition metal compounds with unpaired electrons, these are much less common in organic and main-group chemistry.